IM services over mobile communication networks and the Internet have been put into practice. The current mobile networks that are capable of providing an IM service include 2G, 2.5G, future 3G (3rd Generation), and the IP Multimedia Subsystem (IMS) etc.
There are two kinds of IM systems known in the art. One is Wireless Village (WV) based, which is carried on Hyper Text Transport Protocol (HTTP)/Wireless Access Protocol (WAP)/Short Message Service Protocol (SMS), and supports 2.5G/3G network. The other is SIP/SIMPLE based, which is carried on SIP/SIMPLE, and supports IMS based IP network.
In a chat room of the SIMPLE IM system, there can be a scene demand from a user. Assuming an active SIMPLE IM chat room is presented, if a new user expects to enter the chat room, the SIMPLE IM chat room will be required to provide a data transfer channel for the new user, so that the new user can chat with and transmit messages to other users.
However, the conventional SIP/SIMPLE IM systems may not provide relating solutions or methods to transfer data between the new user and the other users after the new user enters the chat room.